The Niangua darter (Etheostoma nianguae) was listed as a federally threatened species in 1985 and is only known to occur in Missouri. It lives in clear upland creeks and small to medium sized rivers with slight to moderate currents, and require continuously flowing streams with silt-free gravel and rock bottoms. Population declines are primarily due to habitat loss from reservoir construction and stream channelization. Current threats include isolation of the 8 remaining populations by low-water crossings.

The Columbia, MO, Fish and Wildlife Conservation Office and the Fish Passage Program have partnered with the Columbia, MO, Ecological Services Field Office, Federal and State Emergency Management Agencies, Missouri Department of Conservation, and county road crews to increase fish passage for the threatened Niangua darter at Missouri stream crossings. The darter occurs in eleven counties within the Osage River Basin, MO. Several concrete slab type low-water crossings were identified as either preventing movement of the Niangua darter or as modifying stream flow to create unsuitable habitat. Alternative road crossing designs will allow Niangua darter movement, maintain natural stream flow, and allow county commissions to utilize state highway bridge dollars for future repairs.